This invention relates to a new and distinctive corn inbred line designated NP '991 and to hybrids made by using NP 991 as a parent.
Corn (Zea mays) is a valuable and important field crop. Thus, plant breeders are continually developing new and superior corn inbred lines for production of high yielding, agronomically sound hybrids. The goal of the plant breeder is to combine in a single variety or hybrid an improved combination of desirable traits from the parental germplasm. These traits may include maximized yield, resistance to disease and insects, tolerance to drought, heat and other environmental stresses.
Corn hybrid development requires the development of homozygous inbred lines, the crossing of these lines, and the subsequent evaluation of those crosses. Pedigree, backcross, and recurrent selection breeding methods are used to develop inbred lines from breeding populations. Breeding programs combine the genetic backgrounds from two or more inbred lines or various other genetic sources into breeding pools from which new inbred lines are developed by self pollination and selection of desired phenotypes. The new inbred lines are crossed with other inbred lines, and hybrids from these crosses are evaluated to determine which have commercial potential.
Once the inbred parents that give a superior hybrid are identified, the hybrid seed can be reproduced indefinitely as long as inbred parent homogeneity is maintained. Corn hybrids may be either single cross hybrids, produced when two inbred lines are crossed to produce the first generation (F.sub.1) progeny; double cross hybrids, produced from four inbred lines crossed in pairs (A.times.B and C.times.D) and then the two F.sub.1 hybrids are crossed again (A.times.B).times.(C.times.D); or three-way cross hybrids produced from crossing a single cross (A.times.B) to a third inbred line C. Numerous references are available on the topic of corn breeding and hybrid seed corn production; those skilled in the art of corn breeding and production are well aware of techniques and methods for the development of inbred corn lines and corn hybrids. Reference is made particularly to Corn and Corn Improvement, Third Edition, eds. G. F. Sprague and J. W. Dudley, American Society of Agronomy Monograph No. 18, particularly chapters 8 and 9 the substantive content of which is hereby incorporated by reference.